Another lamented that most celebrity profiles are "just fake."

Yet a third griped that MySpace allows corporate entities to create profiles for fictional characters. "Frankly, I think that's going too far," the user wrote.

These are just several of a growing number of disenchanted MySpace users who fret that the site is becoming too corporate, overrun with ads, and less authentic.

As MySpace and other social networking sites have grown, they have drawn more and more ad dollars. Last week, Facebook tapped Microsoft for ads, while MySpace recently forged a similar deal with Google. In addition, ad holding company Interpublic Group recently bought a small stake in Facebook, and promised to purchase ad inventory on the site.

But the very measure of these sites' success--increased advertising spending--leaves the publishers facing a dilemma: Marketers' use of the sites risks diluting the authenticity and appeal of the medium that made it so successful.

Already, users are pushing back against MySpace. Peter Blackshaw--chief marketing officer for Nielsen BuzzMetrics, which monitors online "buzz" about a variety of topics--warns that the growing corporate presence on social networks is a topic of significant discussion among users.

"Advertising can be a huge turn-off if over-deployed," he cautioned. "As advertisers try to figure out the CGM [consumer-generated media] space, they're kind of blurring the line between authentic content creation and advertising. That could definitely backfire."

He added that MySpace was particularly at risk. "MySpace is introducing this more blended form of advertising, in which brands can create their own pages and have their own friends list, and that's the zone that is sort of unproven," he said. "It potentially has a higher turn-off factor because consumers may perceive it as 'over the line.'"

MySpace did not respond to requests for comment for this article.

Rachel Honig, co-founder of the digital-marketing firm Digital Power & Light, agreed that the growing number of fake profiles might quickly prove tiresome. "It's novel, and every [media company] is going to want to have them, but at some point the fictional character isn't going to be able to interact with you anymore, and the novelty will wear off," Honing said. "As a marketer, it's all about creating a long and meaningful relationship with the consumer, and if you leave them feeling sort of cheated, as it were, that's not helping."

Honig added that the growing number of fake profiles--both corporate and user-generated--also cannibalizes the marketing power of the platform overall. "It really dilutes that '100 million' number when some number of those aren't real people. What do I do with that, as a marketer?" she asked. "It's sort of a brick wall you run into."

These issues were highlighted in a recent study by Universal McCann, which found that most users expressed dislike or indifference toward blogs "seeded" with corporate promotions. According to the study, only 10 percent of users said corporate messaging in blogs "can add value to my experience." Presumably, these sentiments translate to social networks like MySpace in some way, although the degree of correlation is unclear.

Professionals aren't the only ones voicing concern about the current approach to social network ads.

Although he is a fervent MySpace supporter, Scott Koboyashi, a co-founder of a "best of MySpace" blog called SpaceCadetz, said in a recent interview that "the site has lost its independent feel."

"It's more noticeable now when profiles are owned by corporations," he said. Koboyashi distinguished these from pages created by up-and-coming bands and graphic artists, which often have a direct hand in the creation of their profiles.

Discussing alternatives to the "fake profile" approach, Honig said Digital Power & Light is helping to create social networks devoted to a particular brand--or even better, an activity associated with a brand. This gives the owner total control over the ad environment, without burying users in their brand. "The true corporate network is better off not branded explicitly," Honig said. "For example, the best NFL social network is not on NFL.com--it would be, say, 'diehardfootballfans.com'--with plenty of room for NFL ads, of course."

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